@for $i from 1 through 20 {
  .pad-#{$i} { padding: #{$i}px; box-sizing: border-box; }
  .pad-l-#{$i} { padding-left: #{$i}px; box-sizing: border-box; }
  .pad-r-#{$i} { padding-right: #{$i}px; box-sizing: border-box; }
  .pad-t-#{$i} { padding-top: #{$i}px; box-sizing: border-box; }
  .pad-b-#{$i} { padding-bottom: #{$i}px; box-sizing: border-box; }
  .pad-lr-#{$i} { padding-left: #{$i}px; padding-right: #{$i}px; box-sizing: border-box; }
  .pad-tb-#{$i} { padding-top: #{$i}px; padding-bottom: #{$i}px; box-sizing: border-box; }
}
